Talk about Pain And Gain! How Bar Paly piled on 20lbs in three weeks by drinking 5000 calorie shakes to play stripper in new movie

She was waif-like at the Hollywood premiere of her new movie Pain And Gain on Monday in a lilac cut-out dress.

But in the film itself, Bar Paly can be seen with a fuller figure.

The rising star revealed that she had to pack on 20lbs in just three weeks to play stripper Sorina Luminita.

Scroll down for trailer

Lean machine: Bar Paly looked super slim at the Pain And Gain premiere on Monday but she had to pile on 20lbs for her role in the film

‘I had to actually gain weight,’ she told reporters at the event. ‘When I started just eating it went to my lower half so I had to start lifting weights for my arms so everything becomes more proportional.’

The Israeli model turned actress drank 5000 calorie shakes in order to bulk up in such a short space of time – and she wasn’t too keen on the taste.

‘I eventually ended up drinking this shake that had 5,000 calories in it, which tastes basically like chocolate flavoured concrete,’ she said.

Fuller figure: The rising star, seen on set of the film in April 2012, drank 5000 calorie shakes to bulk up to play stripper Sorina Luminita

XXX-ercise: The model turned actress said it was hard to keep the weight on because she burned so many calories pole-dancing for her role

But Bar had no choice but to drink the shakes, because the pole-dancing she did for the role would cause her to ‘burn a lot of calories’.

The Michael Bay film will see Bar in plenty of skimpy outfits, Bar has assured.

‘She is the girl who wears everything a little too tight, too short, too inappropriate for the occasion, the Israeli beauty said. ‘She uses her sexuality as a tool ... it's the only thing she knows.’

Purple reign: Bar happily showed off her slender figure as she promoted the movie in a sheer dress

Her time to shine: The stunning Israeli star, pictured right at the film's Miami premiere earlier this month, has been thrust into the spotlight

Bar’s co-stars in the movie, mark Wahlberg and Dwayne ‘The Rock’ Johnson also had to bulk up for the roles.

The movie is based on a true story and sees Marky Mark and The Rock as bodybuilders who get caught up in an extortion ring and kidnapping scheme.

The action comedy film is scheduled for release on April 26 in the US and August 28 in the UK.

Close co-stars: Bar can be seen here with Mark Wahlberg, Rebel Wilson and Anthony Mackie